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CVE-2026-52993 Linux CVE debrief

CVE-2026-52993 is a critical vulnerability in the Linux kernel, specifically in the tipc_buf_append function. The vulnerability arises from the tipc_msg_validate function, which can reallocate the skb it is validating, potentially freeing the original skb. In the tipc_buf_append function, if the skb was reallocated and validation subsequently failed, the error handling path would free the original skb pointer, leading to a double-free. This issue has been resolved by checking if the head now points to a newly allocated reassembled skb and reassigning *headbuf for later freeing operations. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 9.8, indicating a critical severity. The vulnerability was published on June 24, 2026, and last modified on June 28, 2026.

Vendor
Linux
Product
Unknown
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-24
Original CVE updated
2026-08-03
Advisory published
2026-06-24
Advisory updated
2026-08-03

Who should care

This vulnerability affects Linux kernel users and maintainers. Given its critical severity and potential for exploitation, users should prioritize patching their systems. Linux distributions and vendors should also take immediate action to patch and notify their customers.

Technical summary

The tipc_buf_append function in the Linux kernel is vulnerable to a double-free exploit. The tipc_msg_validate function can reallocate the skb, freeing the original. If validation fails, the error handling path frees the original skb pointer, leading to double-free. The fix checks if the head points to a newly allocated skb and reassigns *headbuf. This issue has a CVSS score of 9.8 and is considered critical. The vulnerability was introduced due to a flawed validation and error handling mechanism.

Defensive priority

High priority should be given to patching this vulnerability due to its critical severity and potential for exploitation. Linux kernel users and maintainers should take immediate action to apply the available patches.

Recommended defensive actions

  • Apply the official patches provided by the Linux kernel maintainers.
  • Review and update Linux kernel versions to ensure the patched version is used.
  • Monitor systems for potential exploitation attempts.
  • Perform thorough vulnerability assessments to identify affected systems.
  • Implement compensating controls, such as enhanced monitoring and intrusion detection, until patching can be performed.

Evidence notes

The CVE record and NVD detail provide official information about the vulnerability. The source item URL provides additional context from the NVD database. Multiple source references are available, detailing the commits and patches related to this issue.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-52993 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-52993

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-52993 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-52993

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/0274f24485fc38032d4093e463dc3ff5c7a667c9

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/1d5e589055880fae229e229e1929e087dbe08cf3

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/29940fff14110ca48c5ccc168d121665b51bb778

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/4d104882bc815d4ec666ace9155f5f52715879a6

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/4ee4deadaae7cb2e3d53af0fc889cf92a73413c0

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a438975a6dcdbd70865978c021650d1485586f0b

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d293ca716e7d5dffdaecaf6b9b2f857a33dc3d3a

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.